drm/i915/gem: Free the fence after a fence-chain lookup failure

[linux-2.6-microblaze.git] / drivers / gpu / drm / i915 / gem / i915_gem_execbuffer.c

/*
 * SPDX-License-Identifier: MIT
 *
 * Copyright © 2008,2010 Intel Corporation
 */

#include <linux/intel-iommu.h>
#include <linux/dma-resv.h>
#include <linux/sync_file.h>
#include <linux/uaccess.h>

#include <drm/drm_syncobj.h>

#include "display/intel_frontbuffer.h"

#include "gem/i915_gem_ioctls.h"
#include "gt/intel_context.h"
#include "gt/intel_gt.h"
#include "gt/intel_gt_buffer_pool.h"
#include "gt/intel_gt_pm.h"
#include "gt/intel_ring.h"

#include "i915_drv.h"
#include "i915_gem_clflush.h"
#include "i915_gem_context.h"
#include "i915_gem_ioctls.h"
#include "i915_sw_fence_work.h"
#include "i915_trace.h"
#include "i915_user_extensions.h"

struct eb_vma {
        struct i915_vma *vma;
        unsigned int flags;

        /** This vma's place in the execbuf reservation list */
        struct drm_i915_gem_exec_object2 *exec;
        struct list_head bind_link;
        struct list_head reloc_link;

        struct hlist_node node;
        u32 handle;
};

struct eb_vma_array {
        struct kref kref;
        struct eb_vma vma[];
};

#define __EXEC_OBJECT_HAS_PIN           BIT(31)
#define __EXEC_OBJECT_HAS_FENCE         BIT(30)
#define __EXEC_OBJECT_NEEDS_MAP         BIT(29)
#define __EXEC_OBJECT_NEEDS_BIAS        BIT(28)
#define __EXEC_OBJECT_INTERNAL_FLAGS    (~0u << 28) /* all of the above */

#define __EXEC_HAS_RELOC        BIT(31)
#define __EXEC_INTERNAL_FLAGS   (~0u << 31)
#define UPDATE                  PIN_OFFSET_FIXED

#define BATCH_OFFSET_BIAS (256*1024)

#define __I915_EXEC_ILLEGAL_FLAGS \
        (__I915_EXEC_UNKNOWN_FLAGS | \
         I915_EXEC_CONSTANTS_MASK  | \
         I915_EXEC_RESOURCE_STREAMER)

/* Catch emission of unexpected errors for CI! */
#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM)
#undef EINVAL
#define EINVAL ({ \
        DRM_DEBUG_DRIVER("EINVAL at %s:%d\n", __func__, __LINE__); \
        22; \
})
#endif

/**
 * DOC: User command execution
 *
 * Userspace submits commands to be executed on the GPU as an instruction
 * stream within a GEM object we call a batchbuffer. This instructions may
 * refer to other GEM objects containing auxiliary state such as kernels,
 * samplers, render targets and even secondary batchbuffers. Userspace does
 * not know where in the GPU memory these objects reside and so before the
 * batchbuffer is passed to the GPU for execution, those addresses in the
 * batchbuffer and auxiliary objects are updated. This is known as relocation,
 * or patching. To try and avoid having to relocate each object on the next
 * execution, userspace is told the location of those objects in this pass,
 * but this remains just a hint as the kernel may choose a new location for
 * any object in the future.
 *
 * At the level of talking to the hardware, submitting a batchbuffer for the
 * GPU to execute is to add content to a buffer from which the HW
 * command streamer is reading.
 *
 * 1. Add a command to load the HW context. For Logical Ring Contexts, i.e.
 *    Execlists, this command is not placed on the same buffer as the
 *    remaining items.
 *
 * 2. Add a command to invalidate caches to the buffer.
 *
 * 3. Add a batchbuffer start command to the buffer; the start command is
 *    essentially a token together with the GPU address of the batchbuffer
 *    to be executed.
 *
 * 4. Add a pipeline flush to the buffer.
 *
 * 5. Add a memory write command to the buffer to record when the GPU
 *    is done executing the batchbuffer. The memory write writes the
 *    global sequence number of the request, ``i915_request::global_seqno``;
 *    the i915 driver uses the current value in the register to determine
 *    if the GPU has completed the batchbuffer.
 *
 * 6. Add a user interrupt command to the buffer. This command instructs
 *    the GPU to issue an interrupt when the command, pipeline flush and
 *    memory write are completed.
 *
 * 7. Inform the hardware of the additional commands added to the buffer
 *    (by updating the tail pointer).
 *
 * Processing an execbuf ioctl is conceptually split up into a few phases.
 *
 * 1. Validation - Ensure all the pointers, handles and flags are valid.
 * 2. Reservation - Assign GPU address space for every object
 * 3. Relocation - Update any addresses to point to the final locations
 * 4. Serialisation - Order the request with respect to its dependencies
 * 5. Construction - Construct a request to execute the batchbuffer
 * 6. Submission (at some point in the future execution)
 *
 * Reserving resources for the execbuf is the most complicated phase. We
 * neither want to have to migrate the object in the address space, nor do
 * we want to have to update any relocations pointing to this object. Ideally,
 * we want to leave the object where it is and for all the existing relocations
 * to match. If the object is given a new address, or if userspace thinks the
 * object is elsewhere, we have to parse all the relocation entries and update
 * the addresses. Userspace can set the I915_EXEC_NORELOC flag to hint that
 * all the target addresses in all of its objects match the value in the
 * relocation entries and that they all match the presumed offsets given by the
 * list of execbuffer objects. Using this knowledge, we know that if we haven't
 * moved any buffers, all the relocation entries are valid and we can skip
 * the update. (If userspace is wrong, the likely outcome is an impromptu GPU
 * hang.) The requirement for using I915_EXEC_NO_RELOC are:
 *
 *      The addresses written in the objects must match the corresponding
 *      reloc.presumed_offset which in turn must match the corresponding
 *      execobject.offset.
 *
 *      Any render targets written to in the batch must be flagged with
 *      EXEC_OBJECT_WRITE.
 *
 *      To avoid stalling, execobject.offset should match the current
 *      address of that object within the active context.
 *
 * The reservation is done is multiple phases. First we try and keep any
 * object already bound in its current location - so as long as meets the
 * constraints imposed by the new execbuffer. Any object left unbound after the
 * first pass is then fitted into any available idle space. If an object does
 * not fit, all objects are removed from the reservation and the process rerun
 * after sorting the objects into a priority order (more difficult to fit
 * objects are tried first). Failing that, the entire VM is cleared and we try
 * to fit the execbuf once last time before concluding that it simply will not
 * fit.
 *
 * A small complication to all of this is that we allow userspace not only to
 * specify an alignment and a size for the object in the address space, but
 * we also allow userspace to specify the exact offset. This objects are
 * simpler to place (the location is known a priori) all we have to do is make
 * sure the space is available.
 *
 * Once all the objects are in place, patching up the buried pointers to point
 * to the final locations is a fairly simple job of walking over the relocation
 * entry arrays, looking up the right address and rewriting the value into
 * the object. Simple! ... The relocation entries are stored in user memory
 * and so to access them we have to copy them into a local buffer. That copy
 * has to avoid taking any pagefaults as they may lead back to a GEM object
 * requiring the struct_mutex (i.e. recursive deadlock). So once again we split
 * the relocation into multiple passes. First we try to do everything within an
 * atomic context (avoid the pagefaults) which requires that we never wait. If
 * we detect that we may wait, or if we need to fault, then we have to fallback
 * to a slower path. The slowpath has to drop the mutex. (Can you hear alarm
 * bells yet?) Dropping the mutex means that we lose all the state we have
 * built up so far for the execbuf and we must reset any global data. However,
 * we do leave the objects pinned in their final locations - which is a
 * potential issue for concurrent execbufs. Once we have left the mutex, we can
 * allocate and copy all the relocation entries into a large array at our
 * leisure, reacquire the mutex, reclaim all the objects and other state and
 * then proceed to update any incorrect addresses with the objects.
 *
 * As we process the relocation entries, we maintain a record of whether the
 * object is being written to. Using NORELOC, we expect userspace to provide
 * this information instead. We also check whether we can skip the relocation
 * by comparing the expected value inside the relocation entry with the target's
 * final address. If they differ, we have to map the current object and rewrite
 * the 4 or 8 byte pointer within.
 *
 * Serialising an execbuf is quite simple according to the rules of the GEM
 * ABI. Execution within each context is ordered by the order of submission.
 * Writes to any GEM object are in order of submission and are exclusive. Reads
 * from a GEM object are unordered with respect to other reads, but ordered by
 * writes. A write submitted after a read cannot occur before the read, and
 * similarly any read submitted after a write cannot occur before the write.
 * Writes are ordered between engines such that only one write occurs at any
 * time (completing any reads beforehand) - using semaphores where available
 * and CPU serialisation otherwise. Other GEM access obey the same rules, any
 * write (either via mmaps using set-domain, or via pwrite) must flush all GPU
 * reads before starting, and any read (either using set-domain or pread) must
 * flush all GPU writes before starting. (Note we only employ a barrier before,
 * we currently rely on userspace not concurrently starting a new execution
 * whilst reading or writing to an object. This may be an advantage or not
 * depending on how much you trust userspace not to shoot themselves in the
 * foot.) Serialisation may just result in the request being inserted into
 * a DAG awaiting its turn, but most simple is to wait on the CPU until
 * all dependencies are resolved.
 *
 * After all of that, is just a matter of closing the request and handing it to
 * the hardware (well, leaving it in a queue to be executed). However, we also
 * offer the ability for batchbuffers to be run with elevated privileges so
 * that they access otherwise hidden registers. (Used to adjust L3 cache etc.)
 * Before any batch is given extra privileges we first must check that it
 * contains no nefarious instructions, we check that each instruction is from
 * our whitelist and all registers are also from an allowed list. We first
 * copy the user's batchbuffer to a shadow (so that the user doesn't have
 * access to it, either by the CPU or GPU as we scan it) and then parse each
 * instruction. If everything is ok, we set a flag telling the hardware to run
 * the batchbuffer in trusted mode, otherwise the ioctl is rejected.
 */

struct eb_fence {
        struct drm_syncobj *syncobj; /* Use with ptr_mask_bits() */
        struct dma_fence *dma_fence;
        u64 value;
        struct dma_fence_chain *chain_fence;
};

struct i915_execbuffer {
        struct drm_i915_private *i915; /** i915 backpointer */
        struct drm_file *file; /** per-file lookup tables and limits */
        struct drm_i915_gem_execbuffer2 *args; /** ioctl parameters */
        struct drm_i915_gem_exec_object2 *exec; /** ioctl execobj[] */
        struct eb_vma *vma;

        struct intel_engine_cs *engine; /** engine to queue the request to */
        struct intel_context *context; /* logical state for the request */
        struct i915_gem_context *gem_context; /** caller's context */

        struct i915_request *request; /** our request to build */
        struct eb_vma *batch; /** identity of the batch obj/vma */
        struct i915_vma *trampoline; /** trampoline used for chaining */

        /** actual size of execobj[] as we may extend it for the cmdparser */
        unsigned int buffer_count;

        /** list of vma not yet bound during reservation phase */
        struct list_head unbound;

        /** list of vma that have execobj.relocation_count */
        struct list_head relocs;

        /**
         * Track the most recently used object for relocations, as we
         * frequently have to perform multiple relocations within the same
         * obj/page
         */
        struct reloc_cache {
                struct drm_mm_node node; /** temporary GTT binding */
                unsigned int gen; /** Cached value of INTEL_GEN */
                bool use_64bit_reloc : 1;
                bool has_llc : 1;
                bool has_fence : 1;
                bool needs_unfenced : 1;

                struct i915_vma *target;
                struct i915_request *rq;
                struct i915_vma *rq_vma;
                u32 *rq_cmd;
                unsigned int rq_size;
        } reloc_cache;

        u64 invalid_flags; /** Set of execobj.flags that are invalid */
        u32 context_flags; /** Set of execobj.flags to insert from the ctx */

        u32 batch_start_offset; /** Location within object of batch */
        u32 batch_len; /** Length of batch within object */
        u32 batch_flags; /** Flags composed for emit_bb_start() */

        /**
         * Indicate either the size of the hastable used to resolve
         * relocation handles, or if negative that we are using a direct
         * index into the execobj[].
         */
        int lut_size;
        struct hlist_head *buckets; /** ht for relocation handles */
        struct eb_vma_array *array;

        struct eb_fence *fences;
        unsigned long num_fences;
};

static inline bool eb_use_cmdparser(const struct i915_execbuffer *eb)
{
        return intel_engine_requires_cmd_parser(eb->engine) ||
                (intel_engine_using_cmd_parser(eb->engine) &&
                 eb->args->batch_len);
}

static struct eb_vma_array *eb_vma_array_create(unsigned int count)
{
        struct eb_vma_array *arr;

        arr = kvmalloc(struct_size(arr, vma, count), GFP_KERNEL | __GFP_NOWARN);
        if (!arr)
                return NULL;

        kref_init(&arr->kref);
        arr->vma[0].vma = NULL;

        return arr;
}

static inline void eb_unreserve_vma(struct eb_vma *ev)
{
        struct i915_vma *vma = ev->vma;

        if (unlikely(ev->flags & __EXEC_OBJECT_HAS_FENCE))
                __i915_vma_unpin_fence(vma);

        if (ev->flags & __EXEC_OBJECT_HAS_PIN)
                __i915_vma_unpin(vma);

        ev->flags &= ~(__EXEC_OBJECT_HAS_PIN |
                       __EXEC_OBJECT_HAS_FENCE);
}

static void eb_vma_array_destroy(struct kref *kref)
{
        struct eb_vma_array *arr = container_of(kref, typeof(*arr), kref);
        struct eb_vma *ev = arr->vma;

        while (ev->vma) {
                eb_unreserve_vma(ev);
                i915_vma_put(ev->vma);
                ev++;
        }

        kvfree(arr);
}

static void eb_vma_array_put(struct eb_vma_array *arr)
{
        kref_put(&arr->kref, eb_vma_array_destroy);
}

static int eb_create(struct i915_execbuffer *eb)
{
        /* Allocate an extra slot for use by the command parser + sentinel */
        eb->array = eb_vma_array_create(eb->buffer_count + 2);
        if (!eb->array)
                return -ENOMEM;

        eb->vma = eb->array->vma;

        if (!(eb->args->flags & I915_EXEC_HANDLE_LUT)) {
                unsigned int size = 1 + ilog2(eb->buffer_count);

                /*
                 * Without a 1:1 association between relocation handles and
                 * the execobject[] index, we instead create a hashtable.
                 * We size it dynamically based on available memory, starting
                 * first with 1:1 assocative hash and scaling back until
                 * the allocation succeeds.
                 *
                 * Later on we use a positive lut_size to indicate we are
                 * using this hashtable, and a negative value to indicate a
                 * direct lookup.
                 */
                do {
                        gfp_t flags;

                        /* While we can still reduce the allocation size, don't
                         * raise a warning and allow the allocation to fail.
                         * On the last pass though, we want to try as hard
                         * as possible to perform the allocation and warn
                         * if it fails.
                         */
                        flags = GFP_KERNEL;
                        if (size > 1)
                                flags |= __GFP_NORETRY | __GFP_NOWARN;

                        eb->buckets = kzalloc(sizeof(struct hlist_head) << size,
                                              flags);
                        if (eb->buckets)
                                break;
                } while (--size);

                if (unlikely(!size)) {
                        eb_vma_array_put(eb->array);
                        return -ENOMEM;
                }

                eb->lut_size = size;
        } else {
                eb->lut_size = -eb->buffer_count;
        }

        return 0;
}

static bool
eb_vma_misplaced(const struct drm_i915_gem_exec_object2 *entry,
                 const struct i915_vma *vma,
                 unsigned int flags)
{
        if (vma->node.size < entry->pad_to_size)
                return true;

        if (entry->alignment && !IS_ALIGNED(vma->node.start, entry->alignment))
                return true;

        if (flags & EXEC_OBJECT_PINNED &&
            vma->node.start != entry->offset)
                return true;

        if (flags & __EXEC_OBJECT_NEEDS_BIAS &&
            vma->node.start < BATCH_OFFSET_BIAS)
                return true;

        if (!(flags & EXEC_OBJECT_SUPPORTS_48B_ADDRESS) &&
            (vma->node.start + vma->node.size - 1) >> 32)
                return true;

        if (flags & __EXEC_OBJECT_NEEDS_MAP &&
            !i915_vma_is_map_and_fenceable(vma))
                return true;

        return false;
}

static u64 eb_pin_flags(const struct drm_i915_gem_exec_object2 *entry,
                        unsigned int exec_flags)
{
        u64 pin_flags = 0;

        if (exec_flags & EXEC_OBJECT_NEEDS_GTT)
                pin_flags |= PIN_GLOBAL;

        /*
         * Wa32bitGeneralStateOffset & Wa32bitInstructionBaseOffset,
         * limit address to the first 4GBs for unflagged objects.
         */
        if (!(exec_flags & EXEC_OBJECT_SUPPORTS_48B_ADDRESS))
                pin_flags |= PIN_ZONE_4G;

        if (exec_flags & __EXEC_OBJECT_NEEDS_MAP)
                pin_flags |= PIN_MAPPABLE;

        if (exec_flags & EXEC_OBJECT_PINNED)
                pin_flags |= entry->offset | PIN_OFFSET_FIXED;
        else if (exec_flags & __EXEC_OBJECT_NEEDS_BIAS)
                pin_flags |= BATCH_OFFSET_BIAS | PIN_OFFSET_BIAS;

        return pin_flags;
}

static inline bool
eb_pin_vma(struct i915_execbuffer *eb,
           const struct drm_i915_gem_exec_object2 *entry,
           struct eb_vma *ev)
{
        struct i915_vma *vma = ev->vma;
        u64 pin_flags;

        if (vma->node.size)
                pin_flags = vma->node.start;
        else
                pin_flags = entry->offset & PIN_OFFSET_MASK;

        pin_flags |= PIN_USER | PIN_NOEVICT | PIN_OFFSET_FIXED;
        if (unlikely(ev->flags & EXEC_OBJECT_NEEDS_GTT))
                pin_flags |= PIN_GLOBAL;

        /* Attempt to reuse the current location if available */
        if (unlikely(i915_vma_pin(vma, 0, 0, pin_flags))) {
                if (entry->flags & EXEC_OBJECT_PINNED)
                        return false;

                /* Failing that pick any _free_ space if suitable */
                if (unlikely(i915_vma_pin(vma,
                                          entry->pad_to_size,
                                          entry->alignment,
                                          eb_pin_flags(entry, ev->flags) |
                                          PIN_USER | PIN_NOEVICT)))
                        return false;
        }

        if (unlikely(ev->flags & EXEC_OBJECT_NEEDS_FENCE)) {
                if (unlikely(i915_vma_pin_fence(vma))) {
                        i915_vma_unpin(vma);
                        return false;
                }

                if (vma->fence)
                        ev->flags |= __EXEC_OBJECT_HAS_FENCE;
        }

        ev->flags |= __EXEC_OBJECT_HAS_PIN;
        return !eb_vma_misplaced(entry, vma, ev->flags);
}

static int
eb_validate_vma(struct i915_execbuffer *eb,
                struct drm_i915_gem_exec_object2 *entry,
                struct i915_vma *vma)
{
        if (unlikely(entry->flags & eb->invalid_flags))
                return -EINVAL;

        if (unlikely(entry->alignment &&
                     !is_power_of_2_u64(entry->alignment)))
                return -EINVAL;

        /*
         * Offset can be used as input (EXEC_OBJECT_PINNED), reject
         * any non-page-aligned or non-canonical addresses.
         */
        if (unlikely(entry->flags & EXEC_OBJECT_PINNED &&
                     entry->offset != gen8_canonical_addr(entry->offset & I915_GTT_PAGE_MASK)))
                return -EINVAL;

        /* pad_to_size was once a reserved field, so sanitize it */
        if (entry->flags & EXEC_OBJECT_PAD_TO_SIZE) {
                if (unlikely(offset_in_page(entry->pad_to_size)))
                        return -EINVAL;
        } else {
                entry->pad_to_size = 0;
        }
        /*
         * From drm_mm perspective address space is continuous,
         * so from this point we're always using non-canonical
         * form internally.
         */
        entry->offset = gen8_noncanonical_addr(entry->offset);

        if (!eb->reloc_cache.has_fence) {
                entry->flags &= ~EXEC_OBJECT_NEEDS_FENCE;
        } else {
                if ((entry->flags & EXEC_OBJECT_NEEDS_FENCE ||
                     eb->reloc_cache.needs_unfenced) &&
                    i915_gem_object_is_tiled(vma->obj))
                        entry->flags |= EXEC_OBJECT_NEEDS_GTT | __EXEC_OBJECT_NEEDS_MAP;
        }

        if (!(entry->flags & EXEC_OBJECT_PINNED))
                entry->flags |= eb->context_flags;

        return 0;
}

static void
eb_add_vma(struct i915_execbuffer *eb,
           unsigned int i, unsigned batch_idx,
           struct i915_vma *vma)
{
        struct drm_i915_gem_exec_object2 *entry = &eb->exec[i];
        struct eb_vma *ev = &eb->vma[i];

        GEM_BUG_ON(i915_vma_is_closed(vma));

        ev->vma = vma;
        ev->exec = entry;
        ev->flags = entry->flags;

        if (eb->lut_size > 0) {
                ev->handle = entry->handle;
                hlist_add_head(&ev->node,
                               &eb->buckets[hash_32(entry->handle,
                                                    eb->lut_size)]);
        }

        if (entry->relocation_count)
                list_add_tail(&ev->reloc_link, &eb->relocs);

        /*
         * SNA is doing fancy tricks with compressing batch buffers, which leads
         * to negative relocation deltas. Usually that works out ok since the
         * relocate address is still positive, except when the batch is placed
         * very low in the GTT. Ensure this doesn't happen.
         *
         * Note that actual hangs have only been observed on gen7, but for
         * paranoia do it everywhere.
         */
        if (i == batch_idx) {
                if (entry->relocation_count &&
                    !(ev->flags & EXEC_OBJECT_PINNED))
                        ev->flags |= __EXEC_OBJECT_NEEDS_BIAS;
                if (eb->reloc_cache.has_fence)
                        ev->flags |= EXEC_OBJECT_NEEDS_FENCE;

                eb->batch = ev;
        }

        if (eb_pin_vma(eb, entry, ev)) {
                if (entry->offset != vma->node.start) {
                        entry->offset = vma->node.start | UPDATE;
                        eb->args->flags |= __EXEC_HAS_RELOC;
                }
        } else {
                eb_unreserve_vma(ev);
                list_add_tail(&ev->bind_link, &eb->unbound);
        }
}

static int eb_reserve_vma(const struct i915_execbuffer *eb,
                          struct eb_vma *ev,
                          u64 pin_flags)
{
        struct drm_i915_gem_exec_object2 *entry = ev->exec;
        struct i915_vma *vma = ev->vma;
        int err;

        if (drm_mm_node_allocated(&vma->node) &&
            eb_vma_misplaced(entry, vma, ev->flags)) {
                err = i915_vma_unbind(vma);
                if (err)
                        return err;
        }

        err = i915_vma_pin(vma,
                           entry->pad_to_size, entry->alignment,
                           eb_pin_flags(entry, ev->flags) | pin_flags);
        if (err)
                return err;

        if (entry->offset != vma->node.start) {
                entry->offset = vma->node.start | UPDATE;
                eb->args->flags |= __EXEC_HAS_RELOC;
        }

        if (unlikely(ev->flags & EXEC_OBJECT_NEEDS_FENCE)) {
                err = i915_vma_pin_fence(vma);
                if (unlikely(err)) {
                        i915_vma_unpin(vma);
                        return err;
                }

                if (vma->fence)
                        ev->flags |= __EXEC_OBJECT_HAS_FENCE;
        }

        ev->flags |= __EXEC_OBJECT_HAS_PIN;
        GEM_BUG_ON(eb_vma_misplaced(entry, vma, ev->flags));

        return 0;
}

static int eb_reserve(struct i915_execbuffer *eb)
{
        const unsigned int count = eb->buffer_count;
        unsigned int pin_flags = PIN_USER | PIN_NONBLOCK;
        struct list_head last;
        struct eb_vma *ev;
        unsigned int i, pass;
        int err = 0;

        /*
         * Attempt to pin all of the buffers into the GTT.
         * This is done in 3 phases:
         *
         * 1a. Unbind all objects that do not match the GTT constraints for
         *     the execbuffer (fenceable, mappable, alignment etc).
         * 1b. Increment pin count for already bound objects.
         * 2.  Bind new objects.
         * 3.  Decrement pin count.
         *
         * This avoid unnecessary unbinding of later objects in order to make
         * room for the earlier objects *unless* we need to defragment.
         */

        if (mutex_lock_interruptible(&eb->i915->drm.struct_mutex))
                return -EINTR;

        pass = 0;
        do {
                list_for_each_entry(ev, &eb->unbound, bind_link) {
                        err = eb_reserve_vma(eb, ev, pin_flags);
                        if (err)
                                break;
                }
                if (!(err == -ENOSPC || err == -EAGAIN))
                        break;

                /* Resort *all* the objects into priority order */
                INIT_LIST_HEAD(&eb->unbound);
                INIT_LIST_HEAD(&last);
                for (i = 0; i < count; i++) {
                        unsigned int flags;

                        ev = &eb->vma[i];
                        flags = ev->flags;
                        if (flags & EXEC_OBJECT_PINNED &&
                            flags & __EXEC_OBJECT_HAS_PIN)
                                continue;

                        eb_unreserve_vma(ev);

                        if (flags & EXEC_OBJECT_PINNED)
                                /* Pinned must have their slot */
                                list_add(&ev->bind_link, &eb->unbound);
                        else if (flags & __EXEC_OBJECT_NEEDS_MAP)
                                /* Map require the lowest 256MiB (aperture) */
                                list_add_tail(&ev->bind_link, &eb->unbound);
                        else if (!(flags & EXEC_OBJECT_SUPPORTS_48B_ADDRESS))
                                /* Prioritise 4GiB region for restricted bo */
                                list_add(&ev->bind_link, &last);
                        else
                                list_add_tail(&ev->bind_link, &last);
                }
                list_splice_tail(&last, &eb->unbound);

                if (err == -EAGAIN) {
                        mutex_unlock(&eb->i915->drm.struct_mutex);
                        flush_workqueue(eb->i915->mm.userptr_wq);
                        mutex_lock(&eb->i915->drm.struct_mutex);
                        continue;
                }

                switch (pass++) {
                case 0:
                        break;

                case 1:
                        /* Too fragmented, unbind everything and retry */
                        mutex_lock(&eb->context->vm->mutex);
                        err = i915_gem_evict_vm(eb->context->vm);
                        mutex_unlock(&eb->context->vm->mutex);
                        if (err)
                                goto unlock;
                        break;

                default:
                        err = -ENOSPC;
                        goto unlock;
                }

                pin_flags = PIN_USER;
        } while (1);

unlock:
        mutex_unlock(&eb->i915->drm.struct_mutex);
        return err;
}

static unsigned int eb_batch_index(const struct i915_execbuffer *eb)
{
        if (eb->args->flags & I915_EXEC_BATCH_FIRST)
                return 0;
        else
                return eb->buffer_count - 1;
}

static int eb_select_context(struct i915_execbuffer *eb)
{
        struct i915_gem_context *ctx;

        ctx = i915_gem_context_lookup(eb->file->driver_priv, eb->args->rsvd1);
        if (unlikely(!ctx))
                return -ENOENT;

        eb->gem_context = ctx;
        if (rcu_access_pointer(ctx->vm))
                eb->invalid_flags |= EXEC_OBJECT_NEEDS_GTT;

        eb->context_flags = 0;
        if (test_bit(UCONTEXT_NO_ZEROMAP, &ctx->user_flags))
                eb->context_flags |= __EXEC_OBJECT_NEEDS_BIAS;

        return 0;
}

static int __eb_add_lut(struct i915_execbuffer *eb,
                        u32 handle, struct i915_vma *vma)
{
        struct i915_gem_context *ctx = eb->gem_context;
        struct i915_lut_handle *lut;
        int err;

        lut = i915_lut_handle_alloc();
        if (unlikely(!lut))
                return -ENOMEM;

        i915_vma_get(vma);
        if (!atomic_fetch_inc(&vma->open_count))
                i915_vma_reopen(vma);
        lut->handle = handle;
        lut->ctx = ctx;

        /* Check that the context hasn't been closed in the meantime */
        err = -EINTR;
        if (!mutex_lock_interruptible(&ctx->lut_mutex)) {
                struct i915_address_space *vm = rcu_access_pointer(ctx->vm);

                if (unlikely(vm && vma->vm != vm))
                        err = -EAGAIN; /* user racing with ctx set-vm */
                else if (likely(!i915_gem_context_is_closed(ctx)))
                        err = radix_tree_insert(&ctx->handles_vma, handle, vma);
                else
                        err = -ENOENT;
                if (err == 0) { /* And nor has this handle */
                        struct drm_i915_gem_object *obj = vma->obj;

                        spin_lock(&obj->lut_lock);
                        if (idr_find(&eb->file->object_idr, handle) == obj) {
                                list_add(&lut->obj_link, &obj->lut_list);
                        } else {
                                radix_tree_delete(&ctx->handles_vma, handle);
                                err = -ENOENT;
                        }
                        spin_unlock(&obj->lut_lock);
                }
                mutex_unlock(&ctx->lut_mutex);
        }
        if (unlikely(err))
                goto err;

        return 0;

err:
        i915_vma_close(vma);
        i915_vma_put(vma);
        i915_lut_handle_free(lut);
        return err;
}

static struct i915_vma *eb_lookup_vma(struct i915_execbuffer *eb, u32 handle)
{
        struct i915_address_space *vm = eb->context->vm;

        do {
                struct drm_i915_gem_object *obj;
                struct i915_vma *vma;
                int err;

                rcu_read_lock();
                vma = radix_tree_lookup(&eb->gem_context->handles_vma, handle);
                if (likely(vma && vma->vm == vm))
                        vma = i915_vma_tryget(vma);
                rcu_read_unlock();
                if (likely(vma))
                        return vma;

                obj = i915_gem_object_lookup(eb->file, handle);
                if (unlikely(!obj))
                        return ERR_PTR(-ENOENT);

                vma = i915_vma_instance(obj, vm, NULL);
                if (IS_ERR(vma)) {
                        i915_gem_object_put(obj);
                        return vma;
                }

                err = __eb_add_lut(eb, handle, vma);
                if (likely(!err))
                        return vma;

                i915_gem_object_put(obj);
                if (err != -EEXIST)
                        return ERR_PTR(err);
        } while (1);
}

static int eb_lookup_vmas(struct i915_execbuffer *eb)
{
        unsigned int batch = eb_batch_index(eb);
        unsigned int i;
        int err = 0;

        INIT_LIST_HEAD(&eb->relocs);
        INIT_LIST_HEAD(&eb->unbound);

        for (i = 0; i < eb->buffer_count; i++) {
                struct i915_vma *vma;

                vma = eb_lookup_vma(eb, eb->exec[i].handle);
                if (IS_ERR(vma)) {
                        err = PTR_ERR(vma);
                        break;
                }

                err = eb_validate_vma(eb, &eb->exec[i], vma);
                if (unlikely(err)) {
                        i915_vma_put(vma);
                        break;
                }

                eb_add_vma(eb, i, batch, vma);
        }

        eb->vma[i].vma = NULL;
        return err;
}

static struct eb_vma *
eb_get_vma(const struct i915_execbuffer *eb, unsigned long handle)
{
        if (eb->lut_size < 0) {
                if (handle >= -eb->lut_size)
                        return NULL;
                return &eb->vma[handle];
        } else {
                struct hlist_head *head;
                struct eb_vma *ev;

                head = &eb->buckets[hash_32(handle, eb->lut_size)];
                hlist_for_each_entry(ev, head, node) {
                        if (ev->handle == handle)
                                return ev;
                }
                return NULL;
        }
}

static void eb_destroy(const struct i915_execbuffer *eb)
{
        GEM_BUG_ON(eb->reloc_cache.rq);

        if (eb->array)
                eb_vma_array_put(eb->array);

        if (eb->lut_size > 0)
                kfree(eb->buckets);
}

static inline u64
relocation_target(const struct drm_i915_gem_relocation_entry *reloc,
                  const struct i915_vma *target)
{
        return gen8_canonical_addr((int)reloc->delta + target->node.start);
}

static void reloc_cache_init(struct reloc_cache *cache,
                             struct drm_i915_private *i915)
{
        /* Must be a variable in the struct to allow GCC to unroll. */
        cache->gen = INTEL_GEN(i915);
        cache->has_llc = HAS_LLC(i915);
        cache->use_64bit_reloc = HAS_64BIT_RELOC(i915);
        cache->has_fence = cache->gen < 4;
        cache->needs_unfenced = INTEL_INFO(i915)->unfenced_needs_alignment;
        cache->node.flags = 0;
        cache->rq = NULL;
        cache->target = NULL;
}

#define RELOC_TAIL 4

static int reloc_gpu_chain(struct reloc_cache *cache)
{
        struct intel_gt_buffer_pool_node *pool;
        struct i915_request *rq = cache->rq;
        struct i915_vma *batch;
        u32 *cmd;
        int err;

        pool = intel_gt_get_buffer_pool(rq->engine->gt, PAGE_SIZE);
        if (IS_ERR(pool))
                return PTR_ERR(pool);

        batch = i915_vma_instance(pool->obj, rq->context->vm, NULL);
        if (IS_ERR(batch)) {
                err = PTR_ERR(batch);
                goto out_pool;
        }

        err = i915_vma_pin(batch, 0, 0, PIN_USER | PIN_NONBLOCK);
        if (err)
                goto out_pool;

        GEM_BUG_ON(cache->rq_size + RELOC_TAIL > PAGE_SIZE  / sizeof(u32));
        cmd = cache->rq_cmd + cache->rq_size;
        *cmd++ = MI_ARB_CHECK;
        if (cache->gen >= 8)
                *cmd++ = MI_BATCH_BUFFER_START_GEN8;
        else if (cache->gen >= 6)
                *cmd++ = MI_BATCH_BUFFER_START;
        else
                *cmd++ = MI_BATCH_BUFFER_START | MI_BATCH_GTT;
        *cmd++ = lower_32_bits(batch->node.start);
        *cmd++ = upper_32_bits(batch->node.start); /* Always 0 for gen<8 */
        i915_gem_object_flush_map(cache->rq_vma->obj);
        i915_gem_object_unpin_map(cache->rq_vma->obj);
        cache->rq_vma = NULL;

        err = intel_gt_buffer_pool_mark_active(pool, rq);
        if (err == 0) {
                i915_vma_lock(batch);
                err = i915_request_await_object(rq, batch->obj, false);
                if (err == 0)
                        err = i915_vma_move_to_active(batch, rq, 0);
                i915_vma_unlock(batch);
        }
        i915_vma_unpin(batch);
        if (err)
                goto out_pool;

        cmd = i915_gem_object_pin_map(batch->obj,
                                      cache->has_llc ?
                                      I915_MAP_FORCE_WB :
                                      I915_MAP_FORCE_WC);
        if (IS_ERR(cmd)) {
                err = PTR_ERR(cmd);
                goto out_pool;
        }

        /* Return with batch mapping (cmd) still pinned */
        cache->rq_cmd = cmd;
        cache->rq_size = 0;
        cache->rq_vma = batch;

out_pool:
        intel_gt_buffer_pool_put(pool);
        return err;
}

static unsigned int reloc_bb_flags(const struct reloc_cache *cache)
{
        return cache->gen > 5 ? 0 : I915_DISPATCH_SECURE;
}

static int reloc_gpu_flush(struct reloc_cache *cache)
{
        struct i915_request *rq;
        int err;

        rq = fetch_and_zero(&cache->rq);
        if (!rq)
                return 0;

        if (cache->rq_vma) {
                struct drm_i915_gem_object *obj = cache->rq_vma->obj;

                GEM_BUG_ON(cache->rq_size >= obj->base.size / sizeof(u32));
                cache->rq_cmd[cache->rq_size++] = MI_BATCH_BUFFER_END;

                __i915_gem_object_flush_map(obj,
                                            0, sizeof(u32) * cache->rq_size);
                i915_gem_object_unpin_map(obj);
        }

        err = 0;
        if (rq->engine->emit_init_breadcrumb)
                err = rq->engine->emit_init_breadcrumb(rq);
        if (!err)
                err = rq->engine->emit_bb_start(rq,
                                                rq->batch->node.start,
                                                PAGE_SIZE,
                                                reloc_bb_flags(cache));
        if (err)
                i915_request_set_error_once(rq, err);

        intel_gt_chipset_flush(rq->engine->gt);
        i915_request_add(rq);

        return err;
}

static int reloc_move_to_gpu(struct i915_request *rq, struct i915_vma *vma)
{
        struct drm_i915_gem_object *obj = vma->obj;
        int err;

        i915_vma_lock(vma);

        if (obj->cache_dirty & ~obj->cache_coherent)
                i915_gem_clflush_object(obj, 0);
        obj->write_domain = 0;

        err = i915_request_await_object(rq, vma->obj, true);
        if (err == 0)
                err = i915_vma_move_to_active(vma, rq, EXEC_OBJECT_WRITE);

        i915_vma_unlock(vma);

        return err;
}

static int __reloc_gpu_alloc(struct i915_execbuffer *eb,
                             struct intel_engine_cs *engine,
                             unsigned int len)
{
        struct reloc_cache *cache = &eb->reloc_cache;
        struct intel_gt_buffer_pool_node *pool;
        struct i915_request *rq;
        struct i915_vma *batch;
        u32 *cmd;
        int err;

        pool = intel_gt_get_buffer_pool(engine->gt, PAGE_SIZE);
        if (IS_ERR(pool))
                return PTR_ERR(pool);

        cmd = i915_gem_object_pin_map(pool->obj,
                                      cache->has_llc ?
                                      I915_MAP_FORCE_WB :
                                      I915_MAP_FORCE_WC);
        if (IS_ERR(cmd)) {
                err = PTR_ERR(cmd);
                goto out_pool;
        }

        batch = i915_vma_instance(pool->obj, eb->context->vm, NULL);
        if (IS_ERR(batch)) {
                err = PTR_ERR(batch);
                goto err_unmap;
        }

        err = i915_vma_pin(batch, 0, 0, PIN_USER | PIN_NONBLOCK);
        if (err)
                goto err_unmap;

        if (engine == eb->context->engine) {
                rq = i915_request_create(eb->context);
        } else {
                struct intel_context *ce;

                ce = intel_context_create(engine);
                if (IS_ERR(ce)) {
                        err = PTR_ERR(ce);
                        goto err_unpin;
                }

                i915_vm_put(ce->vm);
                ce->vm = i915_vm_get(eb->context->vm);

                rq = intel_context_create_request(ce);
                intel_context_put(ce);
        }
        if (IS_ERR(rq)) {
                err = PTR_ERR(rq);
                goto err_unpin;
        }

        err = intel_gt_buffer_pool_mark_active(pool, rq);
        if (err)
                goto err_request;

        i915_vma_lock(batch);
        err = i915_request_await_object(rq, batch->obj, false);
        if (err == 0)
                err = i915_vma_move_to_active(batch, rq, 0);
        i915_vma_unlock(batch);
        if (err)
                goto skip_request;

        rq->batch = batch;
        i915_vma_unpin(batch);

        cache->rq = rq;
        cache->rq_cmd = cmd;
        cache->rq_size = 0;
        cache->rq_vma = batch;

        /* Return with batch mapping (cmd) still pinned */
        goto out_pool;

skip_request:
        i915_request_set_error_once(rq, err);
err_request:
        i915_request_add(rq);
err_unpin:
        i915_vma_unpin(batch);
err_unmap:
        i915_gem_object_unpin_map(pool->obj);
out_pool:
        intel_gt_buffer_pool_put(pool);
        return err;
}

static bool reloc_can_use_engine(const struct intel_engine_cs *engine)
{
        return engine->class != VIDEO_DECODE_CLASS || !IS_GEN(engine->i915, 6);
}

static u32 *reloc_gpu(struct i915_execbuffer *eb,
                      struct i915_vma *vma,
                      unsigned int len)
{
        struct reloc_cache *cache = &eb->reloc_cache;
        u32 *cmd;
        int err;

        if (unlikely(!cache->rq)) {
                struct intel_engine_cs *engine = eb->engine;

                if (!reloc_can_use_engine(engine)) {
                        engine = engine->gt->engine_class[COPY_ENGINE_CLASS][0];
                        if (!engine)
                                return ERR_PTR(-ENODEV);
                }

                err = __reloc_gpu_alloc(eb, engine, len);
                if (unlikely(err))
                        return ERR_PTR(err);
        }

        if (vma != cache->target) {
                err = reloc_move_to_gpu(cache->rq, vma);
                if (unlikely(err)) {
                        i915_request_set_error_once(cache->rq, err);
                        return ERR_PTR(err);
                }

                cache->target = vma;
        }

        if (unlikely(cache->rq_size + len >
                     PAGE_SIZE / sizeof(u32) - RELOC_TAIL)) {
                err = reloc_gpu_chain(cache);
                if (unlikely(err)) {
                        i915_request_set_error_once(cache->rq, err);
                        return ERR_PTR(err);
                }
        }

        GEM_BUG_ON(cache->rq_size + len >= PAGE_SIZE  / sizeof(u32));
        cmd = cache->rq_cmd + cache->rq_size;
        cache->rq_size += len;

        return cmd;
}

static unsigned long vma_phys_addr(struct i915_vma *vma, u32 offset)
{
        struct page *page;
        unsigned long addr;

        GEM_BUG_ON(vma->pages != vma->obj->mm.pages);

        page = i915_gem_object_get_page(vma->obj, offset >> PAGE_SHIFT);
        addr = PFN_PHYS(page_to_pfn(page));
        GEM_BUG_ON(overflows_type(addr, u32)); /* expected dma32 */

        return addr + offset_in_page(offset);
}

static int __reloc_entry_gpu(struct i915_execbuffer *eb,
                             struct i915_vma *vma,
                             u64 offset,
                             u64 target_addr)
{
        const unsigned int gen = eb->reloc_cache.gen;
        unsigned int len;
        u32 *batch;
        u64 addr;

        if (gen >= 8)
                len = offset & 7 ? 8 : 5;
        else if (gen >= 4)
                len = 4;
        else
                len = 3;

        batch = reloc_gpu(eb, vma, len);
        if (IS_ERR(batch))
                return PTR_ERR(batch);

        addr = gen8_canonical_addr(vma->node.start + offset);
        if (gen >= 8) {
                if (offset & 7) {
                        *batch++ = MI_STORE_DWORD_IMM_GEN4;
                        *batch++ = lower_32_bits(addr);
                        *batch++ = upper_32_bits(addr);
                        *batch++ = lower_32_bits(target_addr);

                        addr = gen8_canonical_addr(addr + 4);

                        *batch++ = MI_STORE_DWORD_IMM_GEN4;
                        *batch++ = lower_32_bits(addr);
                        *batch++ = upper_32_bits(addr);
                        *batch++ = upper_32_bits(target_addr);
                } else {
                        *batch++ = (MI_STORE_DWORD_IMM_GEN4 | (1 << 21)) + 1;
                        *batch++ = lower_32_bits(addr);
                        *batch++ = upper_32_bits(addr);
                        *batch++ = lower_32_bits(target_addr);
                        *batch++ = upper_32_bits(target_addr);
                }
        } else if (gen >= 6) {
                *batch++ = MI_STORE_DWORD_IMM_GEN4;
                *batch++ = 0;
                *batch++ = addr;
                *batch++ = target_addr;
        } else if (IS_I965G(eb->i915)) {
                *batch++ = MI_STORE_DWORD_IMM_GEN4;
                *batch++ = 0;
                *batch++ = vma_phys_addr(vma, offset);
                *batch++ = target_addr;
        } else if (gen >= 4) {
                *batch++ = MI_STORE_DWORD_IMM_GEN4 | MI_USE_GGTT;
                *batch++ = 0;
                *batch++ = addr;
                *batch++ = target_addr;
        } else if (gen >= 3 &&
                   !(IS_I915G(eb->i915) || IS_I915GM(eb->i915))) {
                *batch++ = MI_STORE_DWORD_IMM | MI_MEM_VIRTUAL;
                *batch++ = addr;
                *batch++ = target_addr;
        } else {
                *batch++ = MI_STORE_DWORD_IMM;
                *batch++ = vma_phys_addr(vma, offset);
                *batch++ = target_addr;
        }

        return 0;
}

static u64
relocate_entry(struct i915_execbuffer *eb,
               struct i915_vma *vma,
               const struct drm_i915_gem_relocation_entry *reloc,
               const struct i915_vma *target)
{
        u64 target_addr = relocation_target(reloc, target);
        int err;

        err = __reloc_entry_gpu(eb, vma, reloc->offset, target_addr);
        if (err)
                return err;

        return target->node.start | UPDATE;
}

static u64
eb_relocate_entry(struct i915_execbuffer *eb,
                  struct eb_vma *ev,
                  const struct drm_i915_gem_relocation_entry *reloc)
{
        struct drm_i915_private *i915 = eb->i915;
        struct eb_vma *target;
        int err;

        /* we've already hold a reference to all valid objects */
        target = eb_get_vma(eb, reloc->target_handle);
        if (unlikely(!target))
                return -ENOENT;

        /* Validate that the target is in a valid r/w GPU domain */
        if (unlikely(reloc->write_domain & (reloc->write_domain - 1))) {
                drm_dbg(&i915->drm, "reloc with multiple write domains: "
                          "target %d offset %d "
                          "read %08x write %08x",
                          reloc->target_handle,
                          (int) reloc->offset,
                          reloc->read_domains,
                          reloc->write_domain);
                return -EINVAL;
        }
        if (unlikely((reloc->write_domain | reloc->read_domains)
                     & ~I915_GEM_GPU_DOMAINS)) {
                drm_dbg(&i915->drm, "reloc with read/write non-GPU domains: "
                          "target %d offset %d "
                          "read %08x write %08x",
                          reloc->target_handle,
                          (int) reloc->offset,
                          reloc->read_domains,
                          reloc->write_domain);
                return -EINVAL;
        }

        if (reloc->write_domain) {
                target->flags |= EXEC_OBJECT_WRITE;

                /*
                 * Sandybridge PPGTT errata: We need a global gtt mapping
                 * for MI and pipe_control writes because the gpu doesn't
                 * properly redirect them through the ppgtt for non_secure
                 * batchbuffers.
                 */
                if (reloc->write_domain == I915_GEM_DOMAIN_INSTRUCTION &&
                    IS_GEN(eb->i915, 6)) {
                        err = i915_vma_bind(target->vma,
                                            target->vma->obj->cache_level,
                                            PIN_GLOBAL, NULL);
                        if (err)
                                return err;
                }
        }

        /*
         * If the relocation already has the right value in it, no
         * more work needs to be done.
         */
        if (gen8_canonical_addr(target->vma->node.start) == reloc->presumed_offset)
                return 0;

        /* Check that the relocation address is valid... */
        if (unlikely(reloc->offset >
                     ev->vma->size - (eb->reloc_cache.use_64bit_reloc ? 8 : 4))) {
                drm_dbg(&i915->drm, "Relocation beyond object bounds: "
                          "target %d offset %d size %d.\n",
                          reloc->target_handle,
                          (int)reloc->offset,
                          (int)ev->vma->size);
                return -EINVAL;
        }
        if (unlikely(reloc->offset & 3)) {
                drm_dbg(&i915->drm, "Relocation not 4-byte aligned: "
                          "target %d offset %d.\n",
                          reloc->target_handle,
                          (int)reloc->offset);
                return -EINVAL;
        }

        /*
         * If we write into the object, we need to force the synchronisation
         * barrier, either with an asynchronous clflush or if we executed the
         * patching using the GPU (though that should be serialised by the
         * timeline). To be completely sure, and since we are required to
         * do relocations we are already stalling, disable the user's opt
         * out of our synchronisation.
         */
        ev->flags &= ~EXEC_OBJECT_ASYNC;

        /* and update the user's relocation entry */
        return relocate_entry(eb, ev->vma, reloc, target->vma);
}

static int eb_relocate_vma(struct i915_execbuffer *eb, struct eb_vma *ev)
{
#define N_RELOC(x) ((x) / sizeof(struct drm_i915_gem_relocation_entry))
        struct drm_i915_gem_relocation_entry stack[N_RELOC(512)];
        const struct drm_i915_gem_exec_object2 *entry = ev->exec;
        struct drm_i915_gem_relocation_entry __user *urelocs =
                u64_to_user_ptr(entry->relocs_ptr);
        unsigned long remain = entry->relocation_count;

        if (unlikely(remain > N_RELOC(ULONG_MAX)))
                return -EINVAL;

        /*
         * We must check that the entire relocation array is safe
         * to read. However, if the array is not writable the user loses
         * the updated relocation values.
         */
        if (unlikely(!access_ok(urelocs, remain * sizeof(*urelocs))))
                return -EFAULT;

        do {
                struct drm_i915_gem_relocation_entry *r = stack;
                unsigned int count =
                        min_t(unsigned long, remain, ARRAY_SIZE(stack));
                unsigned int copied;

                /*
                 * This is the fast path and we cannot handle a pagefault
                 * whilst holding the struct mutex lest the user pass in the
                 * relocations contained within a mmaped bo. For in such a case
                 * we, the page fault handler would call i915_gem_fault() and
                 * we would try to acquire the struct mutex again. Obviously
                 * this is bad and so lockdep complains vehemently.
                 */
                copied = __copy_from_user(r, urelocs, count * sizeof(r[0]));
                if (unlikely(copied))
                        return -EFAULT;

                remain -= count;
                do {
                        u64 offset = eb_relocate_entry(eb, ev, r);

                        if (likely(offset == 0)) {
                        } else if ((s64)offset < 0) {
                                return (int)offset;
                        } else {
                                /*
                                 * Note that reporting an error now
                                 * leaves everything in an inconsistent
                                 * state as we have *already* changed
                                 * the relocation value inside the
                                 * object. As we have not changed the
                                 * reloc.presumed_offset or will not
                                 * change the execobject.offset, on the
                                 * call we may not rewrite the value
                                 * inside the object, leaving it
                                 * dangling and causing a GPU hang. Unless
                                 * userspace dynamically rebuilds the
                                 * relocations on each execbuf rather than
                                 * presume a static tree.
                                 *
                                 * We did previously check if the relocations
                                 * were writable (access_ok), an error now
                                 * would be a strange race with mprotect,
                                 * having already demonstrated that we
                                 * can read from this userspace address.
                                 */
                                offset = gen8_canonical_addr(offset & ~UPDATE);
                                __put_user(offset,
                                           &urelocs[r - stack].presumed_offset);
                        }
                } while (r++, --count);
                urelocs += ARRAY_SIZE(stack);
        } while (remain);

        return 0;
}

static int eb_relocate(struct i915_execbuffer *eb)
{
        int err;

        err = eb_lookup_vmas(eb);
        if (err)
                return err;

        if (!list_empty(&eb->unbound)) {
                err = eb_reserve(eb);
                if (err)
                        return err;
        }

        /* The objects are in their final locations, apply the relocations. */
        if (eb->args->flags & __EXEC_HAS_RELOC) {
                struct eb_vma *ev;
                int flush;

                list_for_each_entry(ev, &eb->relocs, reloc_link) {
                        err = eb_relocate_vma(eb, ev);
                        if (err)
                                break;
                }

                flush = reloc_gpu_flush(&eb->reloc_cache);
                if (!err)
                        err = flush;
        }

        return err;
}

static int eb_move_to_gpu(struct i915_execbuffer *eb)
{
        const unsigned int count = eb->buffer_count;
        struct ww_acquire_ctx acquire;
        unsigned int i;
        int err = 0;

        ww_acquire_init(&acquire, &reservation_ww_class);

        for (i = 0; i < count; i++) {
                struct eb_vma *ev = &eb->vma[i];
                struct i915_vma *vma = ev->vma;

                err = ww_mutex_lock_interruptible(&vma->resv->lock, &acquire);
                if (err == -EDEADLK) {
                        GEM_BUG_ON(i == 0);
                        do {
                                int j = i - 1;

                                ww_mutex_unlock(&eb->vma[j].vma->resv->lock);

                                swap(eb->vma[i],  eb->vma[j]);
                        } while (--i);

                        err = ww_mutex_lock_slow_interruptible(&vma->resv->lock,
                                                               &acquire);
                }
                if (err)
                        break;
        }
        ww_acquire_done(&acquire);

        while (i--) {
                struct eb_vma *ev = &eb->vma[i];
                struct i915_vma *vma = ev->vma;
                unsigned int flags = ev->flags;
                struct drm_i915_gem_object *obj = vma->obj;

                assert_vma_held(vma);

                if (flags & EXEC_OBJECT_CAPTURE) {
                        struct i915_capture_list *capture;

                        capture = kmalloc(sizeof(*capture), GFP_KERNEL);
                        if (capture) {
                                capture->next = eb->request->capture_list;
                                capture->vma = vma;
                                eb->request->capture_list = capture;
                        }
                }

                /*
                 * If the GPU is not _reading_ through the CPU cache, we need
                 * to make sure that any writes (both previous GPU writes from
                 * before a change in snooping levels and normal CPU writes)
                 * caught in that cache are flushed to main memory.
                 *
                 * We want to say
                 *   obj->cache_dirty &&
                 *   !(obj->cache_coherent & I915_BO_CACHE_COHERENT_FOR_READ)
                 * but gcc's optimiser doesn't handle that as well and emits
                 * two jumps instead of one. Maybe one day...
                 */
                if (unlikely(obj->cache_dirty & ~obj->cache_coherent)) {
                        if (i915_gem_clflush_object(obj, 0))
                                flags &= ~EXEC_OBJECT_ASYNC;
                }

                if (err == 0 && !(flags & EXEC_OBJECT_ASYNC)) {
                        err = i915_request_await_object
                                (eb->request, obj, flags & EXEC_OBJECT_WRITE);
                }

                if (err == 0)
                        err = i915_vma_move_to_active(vma, eb->request, flags);

                i915_vma_unlock(vma);
                eb_unreserve_vma(ev);
        }
        ww_acquire_fini(&acquire);

        eb_vma_array_put(fetch_and_zero(&eb->array));

        if (unlikely(err))
                goto err_skip;

        /* Unconditionally flush any chipset caches (for streaming writes). */
        intel_gt_chipset_flush(eb->engine->gt);
        return 0;

err_skip:
        i915_request_set_error_once(eb->request, err);
        return err;
}

static int i915_gem_check_execbuffer(struct drm_i915_gem_execbuffer2 *exec)
{
        if (exec->flags & __I915_EXEC_ILLEGAL_FLAGS)
                return -EINVAL;

        /* Kernel clipping was a DRI1 misfeature */
        if (!(exec->flags & (I915_EXEC_FENCE_ARRAY |
                             I915_EXEC_USE_EXTENSIONS))) {
                if (exec->num_cliprects || exec->cliprects_ptr)
                        return -EINVAL;
        }

        if (exec->DR4 == 0xffffffff) {
                DRM_DEBUG("UXA submitting garbage DR4, fixing up\n");
                exec->DR4 = 0;
        }
        if (exec->DR1 || exec->DR4)
                return -EINVAL;

        if ((exec->batch_start_offset | exec->batch_len) & 0x7)
                return -EINVAL;

        return 0;
}

static int i915_reset_gen7_sol_offsets(struct i915_request *rq)
{
        u32 *cs;
        int i;

        if (!IS_GEN(rq->engine->i915, 7) || rq->engine->id != RCS0) {
                drm_dbg(&rq->engine->i915->drm, "sol reset is gen7/rcs only\n");
                return -EINVAL;
        }

        cs = intel_ring_begin(rq, 4 * 2 + 2);
        if (IS_ERR(cs))
                return PTR_ERR(cs);

        *cs++ = MI_LOAD_REGISTER_IMM(4);
        for (i = 0; i < 4; i++) {
                *cs++ = i915_mmio_reg_offset(GEN7_SO_WRITE_OFFSET(i));
                *cs++ = 0;
        }
        *cs++ = MI_NOOP;
        intel_ring_advance(rq, cs);

        return 0;
}

static struct i915_vma *
shadow_batch_pin(struct drm_i915_gem_object *obj,
                 struct i915_address_space *vm,
                 unsigned int flags)
{
        struct i915_vma *vma;
        int err;

        vma = i915_vma_instance(obj, vm, NULL);
        if (IS_ERR(vma))
                return vma;

        err = i915_vma_pin(vma, 0, 0, flags);
        if (err)
                return ERR_PTR(err);

        return vma;
}

struct eb_parse_work {
        struct dma_fence_work base;
        struct intel_engine_cs *engine;
        struct i915_vma *batch;
        struct i915_vma *shadow;
        struct i915_vma *trampoline;
        unsigned int batch_offset;
        unsigned int batch_length;
};

static int __eb_parse(struct dma_fence_work *work)
{
        struct eb_parse_work *pw = container_of(work, typeof(*pw), base);

        return intel_engine_cmd_parser(pw->engine,
                                       pw->batch,
                                       pw->batch_offset,
                                       pw->batch_length,
                                       pw->shadow,
                                       pw->trampoline);
}

static void __eb_parse_release(struct dma_fence_work *work)
{
        struct eb_parse_work *pw = container_of(work, typeof(*pw), base);

        if (pw->trampoline)
                i915_active_release(&pw->trampoline->active);
        i915_active_release(&pw->shadow->active);
        i915_active_release(&pw->batch->active);
}

static const struct dma_fence_work_ops eb_parse_ops = {
        .name = "eb_parse",
        .work = __eb_parse,
        .release = __eb_parse_release,
};

static inline int
__parser_mark_active(struct i915_vma *vma,
                     struct intel_timeline *tl,
                     struct dma_fence *fence)
{
        struct intel_gt_buffer_pool_node *node = vma->private;

        return i915_active_ref(&node->active, tl->fence_context, fence);
}

static int
parser_mark_active(struct eb_parse_work *pw, struct intel_timeline *tl)
{
        int err;

        mutex_lock(&tl->mutex);

        err = __parser_mark_active(pw->shadow, tl, &pw->base.dma);
        if (err)
                goto unlock;

        if (pw->trampoline) {
                err = __parser_mark_active(pw->trampoline, tl, &pw->base.dma);
                if (err)
                        goto unlock;
        }

unlock:
        mutex_unlock(&tl->mutex);
        return err;
}

static int eb_parse_pipeline(struct i915_execbuffer *eb,
                             struct i915_vma *shadow,
                             struct i915_vma *trampoline)
{
        struct eb_parse_work *pw;
        int err;

        pw = kzalloc(sizeof(*pw), GFP_KERNEL);
        if (!pw)
                return -ENOMEM;

        err = i915_active_acquire(&eb->batch->vma->active);
        if (err)
                goto err_free;

        err = i915_active_acquire(&shadow->active);
        if (err)
                goto err_batch;

        if (trampoline) {
                err = i915_active_acquire(&trampoline->active);
                if (err)
                        goto err_shadow;
        }

        dma_fence_work_init(&pw->base, &eb_parse_ops);

        pw->engine = eb->engine;
        pw->batch = eb->batch->vma;
        pw->batch_offset = eb->batch_start_offset;
        pw->batch_length = eb->batch_len;
        pw->shadow = shadow;
        pw->trampoline = trampoline;

        /* Mark active refs early for this worker, in case we get interrupted */
        err = parser_mark_active(pw, eb->context->timeline);
        if (err)
                goto err_commit;

        err = dma_resv_lock_interruptible(pw->batch->resv, NULL);
        if (err)
                goto err_commit;

        err = dma_resv_reserve_shared(pw->batch->resv, 1);
        if (err)
                goto err_commit_unlock;

        /* Wait for all writes (and relocs) into the batch to complete */
        err = i915_sw_fence_await_reservation(&pw->base.chain,
                                              pw->batch->resv, NULL, false,
                                              0, I915_FENCE_GFP);
        if (err < 0)
                goto err_commit_unlock;

        /* Keep the batch alive and unwritten as we parse */
        dma_resv_add_shared_fence(pw->batch->resv, &pw->base.dma);

        dma_resv_unlock(pw->batch->resv);

        /* Force execution to wait for completion of the parser */
        dma_resv_lock(shadow->resv, NULL);
        dma_resv_add_excl_fence(shadow->resv, &pw->base.dma);
        dma_resv_unlock(shadow->resv);

        dma_fence_work_commit_imm(&pw->base);
        return 0;

err_commit_unlock:
        dma_resv_unlock(pw->batch->resv);
err_commit:
        i915_sw_fence_set_error_once(&pw->base.chain, err);
        dma_fence_work_commit_imm(&pw->base);
        return err;

err_shadow:
        i915_active_release(&shadow->active);
err_batch:
        i915_active_release(&eb->batch->vma->active);
err_free:
        kfree(pw);
        return err;
}

static int eb_parse(struct i915_execbuffer *eb)
{
        struct drm_i915_private *i915 = eb->i915;
        struct intel_gt_buffer_pool_node *pool;
        struct i915_vma *shadow, *trampoline;
        unsigned int len;
        int err;

        if (!eb_use_cmdparser(eb))
                return 0;

        len = eb->batch_len;
        if (!CMDPARSER_USES_GGTT(eb->i915)) {
                /*
                 * ppGTT backed shadow buffers must be mapped RO, to prevent
                 * post-scan tampering
                 */
                if (!eb->context->vm->has_read_only) {
                        drm_dbg(&i915->drm,
                                "Cannot prevent post-scan tampering without RO capable vm\n");
                        return -EINVAL;
                }
        } else {
                len += I915_CMD_PARSER_TRAMPOLINE_SIZE;
        }

        pool = intel_gt_get_buffer_pool(eb->engine->gt, len);
        if (IS_ERR(pool))
                return PTR_ERR(pool);

        shadow = shadow_batch_pin(pool->obj, eb->context->vm, PIN_USER);
        if (IS_ERR(shadow)) {
                err = PTR_ERR(shadow);
                goto err;
        }
        i915_gem_object_set_readonly(shadow->obj);
        shadow->private = pool;

        trampoline = NULL;
        if (CMDPARSER_USES_GGTT(eb->i915)) {
                trampoline = shadow;

                shadow = shadow_batch_pin(pool->obj,
                                          &eb->engine->gt->ggtt->vm,
                                          PIN_GLOBAL);
                if (IS_ERR(shadow)) {
                        err = PTR_ERR(shadow);
                        shadow = trampoline;
                        goto err_shadow;
                }
                shadow->private = pool;

                eb->batch_flags |= I915_DISPATCH_SECURE;
        }

        err = eb_parse_pipeline(eb, shadow, trampoline);
        if (err)
                goto err_trampoline;

        eb->vma[eb->buffer_count].vma = i915_vma_get(shadow);
        eb->vma[eb->buffer_count].flags = __EXEC_OBJECT_HAS_PIN;
        eb->batch = &eb->vma[eb->buffer_count++];
        eb->vma[eb->buffer_count].vma = NULL;

        eb->trampoline = trampoline;
        eb->batch_start_offset = 0;

        return 0;

err_trampoline:
        if (trampoline)
                i915_vma_unpin(trampoline);
err_shadow:
        i915_vma_unpin(shadow);
err:
        intel_gt_buffer_pool_put(pool);
        return err;
}

static int eb_submit(struct i915_execbuffer *eb, struct i915_vma *batch)
{
        int err;

        err = eb_move_to_gpu(eb);
        if (err)
                return err;

        if (eb->args->flags & I915_EXEC_GEN7_SOL_RESET) {
                err = i915_reset_gen7_sol_offsets(eb->request);
                if (err)
                        return err;
        }

        /*
         * After we completed waiting for other engines (using HW semaphores)
         * then we can signal that this request/batch is ready to run. This
         * allows us to determine if the batch is still waiting on the GPU
         * or actually running by checking the breadcrumb.
         */
        if (eb->engine->emit_init_breadcrumb) {
                err = eb->engine->emit_init_breadcrumb(eb->request);
                if (err)
                        return err;
        }

        err = eb->engine->emit_bb_start(eb->request,
                                        batch->node.start +
                                        eb->batch_start_offset,
                                        eb->batch_len,
                                        eb->batch_flags);
        if (err)
                return err;

        if (eb->trampoline) {
                GEM_BUG_ON(eb->batch_start_offset);
                err = eb->engine->emit_bb_start(eb->request,
                                                eb->trampoline->node.start +
                                                eb->batch_len,
                                                0, 0);
                if (err)
                        return err;
        }

        if (intel_context_nopreempt(eb->context))
                __set_bit(I915_FENCE_FLAG_NOPREEMPT, &eb->request->fence.flags);

        return 0;
}

static int num_vcs_engines(const struct drm_i915_private *i915)
{
        return hweight64(VDBOX_MASK(&i915->gt));
}

/*
 * Find one BSD ring to dispatch the corresponding BSD command.
 * The engine index is returned.
 */
static unsigned int
gen8_dispatch_bsd_engine(struct drm_i915_private *dev_priv,
                         struct drm_file *file)
{
        struct drm_i915_file_private *file_priv = file->driver_priv;

        /* Check whether the file_priv has already selected one ring. */
        if ((int)file_priv->bsd_engine < 0)
                file_priv->bsd_engine =
                        get_random_int() % num_vcs_engines(dev_priv);

        return file_priv->bsd_engine;
}

static const enum intel_engine_id user_ring_map[] = {
        [I915_EXEC_DEFAULT]     = RCS0,
        [I915_EXEC_RENDER]      = RCS0,
        [I915_EXEC_BLT]         = BCS0,
        [I915_EXEC_BSD]         = VCS0,
        [I915_EXEC_VEBOX]       = VECS0
};

static struct i915_request *eb_throttle(struct intel_context *ce)
{
        struct intel_ring *ring = ce->ring;
        struct intel_timeline *tl = ce->timeline;
        struct i915_request *rq;

        /*
         * Completely unscientific finger-in-the-air estimates for suitable
         * maximum user request size (to avoid blocking) and then backoff.
         */
        if (intel_ring_update_space(ring) >= PAGE_SIZE)
                return NULL;

        /*
         * Find a request that after waiting upon, there will be at least half
         * the ring available. The hysteresis allows us to compete for the
         * shared ring and should mean that we sleep less often prior to
         * claiming our resources, but not so long that the ring completely
         * drains before we can submit our next request.
         */
        list_for_each_entry(rq, &tl->requests, link) {
                if (rq->ring != ring)
                        continue;

                if (__intel_ring_space(rq->postfix,
                                       ring->emit, ring->size) > ring->size / 2)
                        break;
        }
        if (&rq->link == &tl->requests)
                return NULL; /* weird, we will check again later for real */

        return i915_request_get(rq);
}

static int __eb_pin_engine(struct i915_execbuffer *eb, struct intel_context *ce)
{
        struct intel_timeline *tl;
        struct i915_request *rq;
        int err;

        /*
         * ABI: Before userspace accesses the GPU (e.g. execbuffer), report
         * EIO if the GPU is already wedged.
         */
        err = intel_gt_terminally_wedged(ce->engine->gt);
        if (err)
                return err;

        if (unlikely(intel_context_is_banned(ce)))
                return -EIO;

        /*
         * Pinning the contexts may generate requests in order to acquire
         * GGTT space, so do this first before we reserve a seqno for
         * ourselves.
         */
        err = intel_context_pin(ce);
        if (err)
                return err;

        /*
         * Take a local wakeref for preparing to dispatch the execbuf as
         * we expect to access the hardware fairly frequently in the
         * process, and require the engine to be kept awake between accesses.
         * Upon dispatch, we acquire another prolonged wakeref that we hold
         * until the timeline is idle, which in turn releases the wakeref
         * taken on the engine, and the parent device.
         */
        tl = intel_context_timeline_lock(ce);
        if (IS_ERR(tl)) {
                err = PTR_ERR(tl);
                goto err_unpin;
        }

        intel_context_enter(ce);
        rq = eb_throttle(ce);

        intel_context_timeline_unlock(tl);

        if (rq) {
                bool nonblock = eb->file->filp->f_flags & O_NONBLOCK;
                long timeout;

                timeout = MAX_SCHEDULE_TIMEOUT;
                if (nonblock)
                        timeout = 0;

                timeout = i915_request_wait(rq,
                                            I915_WAIT_INTERRUPTIBLE,
                                            timeout);
                i915_request_put(rq);

                if (timeout < 0) {
                        err = nonblock ? -EWOULDBLOCK : timeout;
                        goto err_exit;
                }
        }

        eb->engine = ce->engine;
        eb->context = ce;
        return 0;

err_exit:
        mutex_lock(&tl->mutex);
        intel_context_exit(ce);
        intel_context_timeline_unlock(tl);
err_unpin:
        intel_context_unpin(ce);
        return err;
}

static void eb_unpin_engine(struct i915_execbuffer *eb)
{
        struct intel_context *ce = eb->context;
        struct intel_timeline *tl = ce->timeline;

        mutex_lock(&tl->mutex);
        intel_context_exit(ce);
        mutex_unlock(&tl->mutex);

        intel_context_unpin(ce);
}

static unsigned int
eb_select_legacy_ring(struct i915_execbuffer *eb,
                      struct drm_file *file,
                      struct drm_i915_gem_execbuffer2 *args)
{
        struct drm_i915_private *i915 = eb->i915;
        unsigned int user_ring_id = args->flags & I915_EXEC_RING_MASK;

        if (user_ring_id != I915_EXEC_BSD &&
            (args->flags & I915_EXEC_BSD_MASK)) {
                drm_dbg(&i915->drm,
                        "execbuf with non bsd ring but with invalid "
                        "bsd dispatch flags: %d\n", (int)(args->flags));
                return -1;
        }

        if (user_ring_id == I915_EXEC_BSD && num_vcs_engines(i915) > 1) {
                unsigned int bsd_idx = args->flags & I915_EXEC_BSD_MASK;

                if (bsd_idx == I915_EXEC_BSD_DEFAULT) {
                        bsd_idx = gen8_dispatch_bsd_engine(i915, file);
                } else if (bsd_idx >= I915_EXEC_BSD_RING1 &&
                           bsd_idx <= I915_EXEC_BSD_RING2) {
                        bsd_idx >>= I915_EXEC_BSD_SHIFT;
                        bsd_idx--;
                } else {
                        drm_dbg(&i915->drm,
                                "execbuf with unknown bsd ring: %u\n",
                                bsd_idx);
                        return -1;
                }

                return _VCS(bsd_idx);
        }

        if (user_ring_id >= ARRAY_SIZE(user_ring_map)) {
                drm_dbg(&i915->drm, "execbuf with unknown ring: %u\n",
                        user_ring_id);
                return -1;
        }

        return user_ring_map[user_ring_id];
}

static int
eb_pin_engine(struct i915_execbuffer *eb,
              struct drm_file *file,
              struct drm_i915_gem_execbuffer2 *args)
{
        struct intel_context *ce;
        unsigned int idx;
        int err;

        if (i915_gem_context_user_engines(eb->gem_context))
                idx = args->flags & I915_EXEC_RING_MASK;
        else
                idx = eb_select_legacy_ring(eb, file, args);

        ce = i915_gem_context_get_engine(eb->gem_context, idx);
        if (IS_ERR(ce))
                return PTR_ERR(ce);

        err = __eb_pin_engine(eb, ce);
        intel_context_put(ce);

        return err;
}

static void
__free_fence_array(struct eb_fence *fences, unsigned int n)
{
        while (n--) {
                drm_syncobj_put(ptr_mask_bits(fences[n].syncobj, 2));
                dma_fence_put(fences[n].dma_fence);
                kfree(fences[n].chain_fence);
        }
        kvfree(fences);
}

static int
add_timeline_fence_array(struct i915_execbuffer *eb,
                         const struct drm_i915_gem_execbuffer_ext_timeline_fences *timeline_fences)
{
        struct drm_i915_gem_exec_fence __user *user_fences;
        u64 __user *user_values;
        struct eb_fence *f;
        u64 nfences;
        int err = 0;

        nfences = timeline_fences->fence_count;
        if (!nfences)
                return 0;

        /* Check multiplication overflow for access_ok() and kvmalloc_array() */
        BUILD_BUG_ON(sizeof(size_t) > sizeof(unsigned long));
        if (nfences > min_t(unsigned long,
                            ULONG_MAX / sizeof(*user_fences),
                            SIZE_MAX / sizeof(*f)) - eb->num_fences)
                return -EINVAL;

        user_fences = u64_to_user_ptr(timeline_fences->handles_ptr);
        if (!access_ok(user_fences, nfences * sizeof(*user_fences)))
                return -EFAULT;

        user_values = u64_to_user_ptr(timeline_fences->values_ptr);
        if (!access_ok(user_values, nfences * sizeof(*user_values)))
                return -EFAULT;

        f = krealloc(eb->fences,
                     (eb->num_fences + nfences) * sizeof(*f),
                     __GFP_NOWARN | GFP_KERNEL);
        if (!f)
                return -ENOMEM;

        eb->fences = f;
        f += eb->num_fences;

        BUILD_BUG_ON(~(ARCH_KMALLOC_MINALIGN - 1) &
                     ~__I915_EXEC_FENCE_UNKNOWN_FLAGS);

        while (nfences--) {
                struct drm_i915_gem_exec_fence user_fence;
                struct drm_syncobj *syncobj;
                struct dma_fence *fence = NULL;
                u64 point;

                if (__copy_from_user(&user_fence,
                                     user_fences++,
                                     sizeof(user_fence)))
                        return -EFAULT;

                if (user_fence.flags & __I915_EXEC_FENCE_UNKNOWN_FLAGS)
                        return -EINVAL;

                if (__get_user(point, user_values++))
                        return -EFAULT;

                syncobj = drm_syncobj_find(eb->file, user_fence.handle);
                if (!syncobj) {
                        DRM_DEBUG("Invalid syncobj handle provided\n");
                        return -ENOENT;
                }

                fence = drm_syncobj_fence_get(syncobj);

                if (!fence && user_fence.flags &&
                    !(user_fence.flags & I915_EXEC_FENCE_SIGNAL)) {
                        DRM_DEBUG("Syncobj handle has no fence\n");
                        drm_syncobj_put(syncobj);
                        return -EINVAL;
                }

                if (fence)
                        err = dma_fence_chain_find_seqno(&fence, point);

                if (err && !(user_fence.flags & I915_EXEC_FENCE_SIGNAL)) {
                        DRM_DEBUG("Syncobj handle missing requested point %llu\n", point);
                        dma_fence_put(fence);
                        drm_syncobj_put(syncobj);
                        return err;
                }

                /*
                 * A point might have been signaled already and
                 * garbage collected from the timeline. In this case
                 * just ignore the point and carry on.
                 */
                if (!fence && !(user_fence.flags & I915_EXEC_FENCE_SIGNAL)) {
                        drm_syncobj_put(syncobj);
                        continue;
                }

                /*
                 * For timeline syncobjs we need to preallocate chains for
                 * later signaling.
                 */
                if (point != 0 && user_fence.flags & I915_EXEC_FENCE_SIGNAL) {
                        /*
                         * Waiting and signaling the same point (when point !=
                         * 0) would break the timeline.
                         */
                        if (user_fence.flags & I915_EXEC_FENCE_WAIT) {
                                DRM_DEBUG("Trying to wait & signal the same timeline point.\n");
                                dma_fence_put(fence);
                                drm_syncobj_put(syncobj);
                                return -EINVAL;
                        }

                        f->chain_fence =
                                kmalloc(sizeof(*f->chain_fence),
                                        GFP_KERNEL);
                        if (!f->chain_fence) {
                                drm_syncobj_put(syncobj);
                                dma_fence_put(fence);
                                return -ENOMEM;
                        }
                } else {
                        f->chain_fence = NULL;
                }

                f->syncobj = ptr_pack_bits(syncobj, user_fence.flags, 2);
                f->dma_fence = fence;
                f->value = point;
                f++;
                eb->num_fences++;
        }

        return 0;
}

static int add_fence_array(struct i915_execbuffer *eb)
{
        struct drm_i915_gem_execbuffer2 *args = eb->args;
        struct drm_i915_gem_exec_fence __user *user;
        unsigned long num_fences = args->num_cliprects;
        struct eb_fence *f;

        if (!(args->flags & I915_EXEC_FENCE_ARRAY))
                return 0;

        if (!num_fences)
                return 0;

        /* Check multiplication overflow for access_ok() and kvmalloc_array() */
        BUILD_BUG_ON(sizeof(size_t) > sizeof(unsigned long));
        if (num_fences > min_t(unsigned long,
                               ULONG_MAX / sizeof(*user),
                               SIZE_MAX / sizeof(*f) - eb->num_fences))
                return -EINVAL;

        user = u64_to_user_ptr(args->cliprects_ptr);
        if (!access_ok(user, num_fences * sizeof(*user)))
                return -EFAULT;

        f = krealloc(eb->fences,
                     (eb->num_fences + num_fences) * sizeof(*f),
                     __GFP_NOWARN | GFP_KERNEL);
        if (!f)
                return -ENOMEM;

        eb->fences = f;
        f += eb->num_fences;
        while (num_fences--) {
                struct drm_i915_gem_exec_fence user_fence;
                struct drm_syncobj *syncobj;
                struct dma_fence *fence = NULL;

                if (__copy_from_user(&user_fence, user++, sizeof(user_fence)))
                        return -EFAULT;

                if (user_fence.flags & __I915_EXEC_FENCE_UNKNOWN_FLAGS)
                        return -EINVAL;

                syncobj = drm_syncobj_find(eb->file, user_fence.handle);
                if (!syncobj) {
                        DRM_DEBUG("Invalid syncobj handle provided\n");
                        return -ENOENT;
                }

                if (user_fence.flags & I915_EXEC_FENCE_WAIT) {
                        fence = drm_syncobj_fence_get(syncobj);
                        if (!fence) {
                                DRM_DEBUG("Syncobj handle has no fence\n");
                                drm_syncobj_put(syncobj);
                                return -EINVAL;
                        }
                }

                BUILD_BUG_ON(~(ARCH_KMALLOC_MINALIGN - 1) &
                             ~__I915_EXEC_FENCE_UNKNOWN_FLAGS);

                f->syncobj = ptr_pack_bits(syncobj, user_fence.flags, 2);
                f->dma_fence = fence;
                f->value = 0;
                f->chain_fence = NULL;
                f++;
                eb->num_fences++;
        }

        return 0;
}

static void put_fence_array(struct eb_fence *fences, int num_fences)
{
        if (fences)
                __free_fence_array(fences, num_fences);
}

static int
await_fence_array(struct i915_execbuffer *eb)
{
        unsigned int n;
        int err;

        for (n = 0; n < eb->num_fences; n++) {
                struct drm_syncobj *syncobj;
                unsigned int flags;

                syncobj = ptr_unpack_bits(eb->fences[n].syncobj, &flags, 2);

                if (!eb->fences[n].dma_fence)
                        continue;

                err = i915_request_await_dma_fence(eb->request,
                                                   eb->fences[n].dma_fence);
                if (err < 0)
                        return err;
        }

        return 0;
}

static void signal_fence_array(const struct i915_execbuffer *eb)
{
        struct dma_fence * const fence = &eb->request->fence;
        unsigned int n;

        for (n = 0; n < eb->num_fences; n++) {
                struct drm_syncobj *syncobj;
                unsigned int flags;

                syncobj = ptr_unpack_bits(eb->fences[n].syncobj, &flags, 2);
                if (!(flags & I915_EXEC_FENCE_SIGNAL))
                        continue;

                if (eb->fences[n].chain_fence) {
                        drm_syncobj_add_point(syncobj,
                                              eb->fences[n].chain_fence,
                                              fence,
                                              eb->fences[n].value);
                        /*
                         * The chain's ownership is transferred to the
                         * timeline.
                         */
                        eb->fences[n].chain_fence = NULL;
                } else {
                        drm_syncobj_replace_fence(syncobj, fence);
                }
        }
}

static int
parse_timeline_fences(struct i915_user_extension __user *ext, void *data)
{
        struct i915_execbuffer *eb = data;
        struct drm_i915_gem_execbuffer_ext_timeline_fences timeline_fences;

        if (copy_from_user(&timeline_fences, ext, sizeof(timeline_fences)))
                return -EFAULT;

        return add_timeline_fence_array(eb, &timeline_fences);
}

static void retire_requests(struct intel_timeline *tl, struct i915_request *end)
{
        struct i915_request *rq, *rn;

        list_for_each_entry_safe(rq, rn, &tl->requests, link)
                if (rq == end || !i915_request_retire(rq))
                        break;
}

static void eb_request_add(struct i915_execbuffer *eb)
{
        struct i915_request *rq = eb->request;
        struct intel_timeline * const tl = i915_request_timeline(rq);
        struct i915_sched_attr attr = {};
        struct i915_request *prev;

        lockdep_assert_held(&tl->mutex);
        lockdep_unpin_lock(&tl->mutex, rq->cookie);

        trace_i915_request_add(rq);

        prev = __i915_request_commit(rq);

        /* Check that the context wasn't destroyed before submission */
        if (likely(!intel_context_is_closed(eb->context))) {
                attr = eb->gem_context->sched;
        } else {
                /* Serialise with context_close via the add_to_timeline */
                i915_request_set_error_once(rq, -ENOENT);
                __i915_request_skip(rq);
        }

        __i915_request_queue(rq, &attr);

        /* Try to clean up the client's timeline after submitting the request */
        if (prev)
                retire_requests(tl, prev);

        mutex_unlock(&tl->mutex);
}

static const i915_user_extension_fn execbuf_extensions[] = {
        [DRM_I915_GEM_EXECBUFFER_EXT_TIMELINE_FENCES] = parse_timeline_fences,
};

static int
parse_execbuf2_extensions(struct drm_i915_gem_execbuffer2 *args,
                          struct i915_execbuffer *eb)
{
        if (!(args->flags & I915_EXEC_USE_EXTENSIONS))
                return 0;

        /* The execbuf2 extension mechanism reuses cliprects_ptr. So we cannot
         * have another flag also using it at the same time.
         */
        if (eb->args->flags & I915_EXEC_FENCE_ARRAY)
                return -EINVAL;

        if (args->num_cliprects != 0)
                return -EINVAL;

        return i915_user_extensions(u64_to_user_ptr(args->cliprects_ptr),
                                    execbuf_extensions,
                                    ARRAY_SIZE(execbuf_extensions),
                                    eb);
}

static int
i915_gem_do_execbuffer(struct drm_device *dev,
                       struct drm_file *file,
                       struct drm_i915_gem_execbuffer2 *args,
                       struct drm_i915_gem_exec_object2 *exec)
{
        struct drm_i915_private *i915 = to_i915(dev);
        struct i915_execbuffer eb;
        struct dma_fence *in_fence = NULL;
        struct sync_file *out_fence = NULL;
        struct i915_vma *batch;
        int out_fence_fd = -1;
        int err;

        BUILD_BUG_ON(__EXEC_INTERNAL_FLAGS & ~__I915_EXEC_ILLEGAL_FLAGS);
        BUILD_BUG_ON(__EXEC_OBJECT_INTERNAL_FLAGS &
                     ~__EXEC_OBJECT_UNKNOWN_FLAGS);

        eb.i915 = i915;
        eb.file = file;
        eb.args = args;
        if (!(args->flags & I915_EXEC_NO_RELOC))
                args->flags |= __EXEC_HAS_RELOC;

        eb.exec = exec;

        eb.invalid_flags = __EXEC_OBJECT_UNKNOWN_FLAGS;
        reloc_cache_init(&eb.reloc_cache, eb.i915);

        eb.buffer_count = args->buffer_count;
        eb.batch_start_offset = args->batch_start_offset;
        eb.batch_len = args->batch_len;
        eb.trampoline = NULL;

        eb.fences = NULL;
        eb.num_fences = 0;

        eb.batch_flags = 0;
        if (args->flags & I915_EXEC_SECURE) {
                if (INTEL_GEN(i915) >= 11)
                        return -ENODEV;

                /* Return -EPERM to trigger fallback code on old binaries. */
                if (!HAS_SECURE_BATCHES(i915))
                        return -EPERM;

                if (!drm_is_current_master(file) || !capable(CAP_SYS_ADMIN))
                        return -EPERM;

                eb.batch_flags |= I915_DISPATCH_SECURE;
        }
        if (args->flags & I915_EXEC_IS_PINNED)
                eb.batch_flags |= I915_DISPATCH_PINNED;

        err = parse_execbuf2_extensions(args, &eb);
        if (err)
                goto err_ext;

        err = add_fence_array(&eb);
        if (err)
                goto err_ext;

#define IN_FENCES (I915_EXEC_FENCE_IN | I915_EXEC_FENCE_SUBMIT)
        if (args->flags & IN_FENCES) {
                if ((args->flags & IN_FENCES) == IN_FENCES)
                        return -EINVAL;

                in_fence = sync_file_get_fence(lower_32_bits(args->rsvd2));
                if (!in_fence) {
                        err = -EINVAL;
                        goto err_ext;
                }
        }
#undef IN_FENCES

        if (args->flags & I915_EXEC_FENCE_OUT) {
                out_fence_fd = get_unused_fd_flags(O_CLOEXEC);
                if (out_fence_fd < 0) {
                        err = out_fence_fd;
                        goto err_in_fence;
                }
        }

        err = eb_create(&eb);
        if (err)
                goto err_out_fence;

        GEM_BUG_ON(!eb.lut_size);

        err = eb_select_context(&eb);
        if (unlikely(err))
                goto err_destroy;

        err = eb_pin_engine(&eb, file, args);
        if (unlikely(err))
                goto err_context;

        err = eb_relocate(&eb);
        if (err) {
                /*
                 * If the user expects the execobject.offset and
                 * reloc.presumed_offset to be an exact match,
                 * as for using NO_RELOC, then we cannot update
                 * the execobject.offset until we have completed
                 * relocation.
                 */
                args->flags &= ~__EXEC_HAS_RELOC;
                goto err_vma;
        }

        if (unlikely(eb.batch->flags & EXEC_OBJECT_WRITE)) {
                drm_dbg(&i915->drm,
                        "Attempting to use self-modifying batch buffer\n");
                err = -EINVAL;
                goto err_vma;
        }

        if (range_overflows_t(u64,
                              eb.batch_start_offset, eb.batch_len,
                              eb.batch->vma->size)) {
                drm_dbg(&i915->drm, "Attempting to use out-of-bounds batch\n");
                err = -EINVAL;
                goto err_vma;
        }

        if (eb.batch_len == 0)
                eb.batch_len = eb.batch->vma->size - eb.batch_start_offset;

        err = eb_parse(&eb);
        if (err)
                goto err_vma;

        /*
         * snb/ivb/vlv conflate the "batch in ppgtt" bit with the "non-secure
         * batch" bit. Hence we need to pin secure batches into the global gtt.
         * hsw should have this fixed, but bdw mucks it up again. */
        batch = eb.batch->vma;
        if (eb.batch_flags & I915_DISPATCH_SECURE) {
                struct i915_vma *vma;

                /*
                 * So on first glance it looks freaky that we pin the batch here
                 * outside of the reservation loop. But:
                 * - The batch is already pinned into the relevant ppgtt, so we
                 *   already have the backing storage fully allocated.
                 * - No other BO uses the global gtt (well contexts, but meh),
                 *   so we don't really have issues with multiple objects not
                 *   fitting due to fragmentation.
                 * So this is actually safe.
                 */
                vma = i915_gem_object_ggtt_pin(batch->obj, NULL, 0, 0, 0);
                if (IS_ERR(vma)) {
                        err = PTR_ERR(vma);
                        goto err_parse;
                }

                batch = vma;
        }

        /* All GPU relocation batches must be submitted prior to the user rq */
        GEM_BUG_ON(eb.reloc_cache.rq);

        /* Allocate a request for this batch buffer nice and early. */
        eb.request = i915_request_create(eb.context);
        if (IS_ERR(eb.request)) {
                err = PTR_ERR(eb.request);
                goto err_batch_unpin;
        }

        if (in_fence) {
                if (args->flags & I915_EXEC_FENCE_SUBMIT)
                        err = i915_request_await_execution(eb.request,
                                                           in_fence,
                                                           eb.engine->bond_execute);
                else
                        err = i915_request_await_dma_fence(eb.request,
                                                           in_fence);
                if (err < 0)
                        goto err_request;
        }

        if (eb.fences) {
                err = await_fence_array(&eb);
                if (err)
                        goto err_request;
        }

        if (out_fence_fd != -1) {
                out_fence = sync_file_create(&eb.request->fence);
                if (!out_fence) {
                        err = -ENOMEM;
                        goto err_request;
                }
        }

        /*
         * Whilst this request exists, batch_obj will be on the
         * active_list, and so will hold the active reference. Only when this
         * request is retired will the the batch_obj be moved onto the
         * inactive_list and lose its active reference. Hence we do not need
         * to explicitly hold another reference here.
         */
        eb.request->batch = batch;
        if (batch->private)
                intel_gt_buffer_pool_mark_active(batch->private, eb.request);

        trace_i915_request_queue(eb.request, eb.batch_flags);
        err = eb_submit(&eb, batch);
err_request:
        i915_request_get(eb.request);
        eb_request_add(&eb);

        if (eb.fences)
                signal_fence_array(&eb);

        if (out_fence) {
                if (err == 0) {
                        fd_install(out_fence_fd, out_fence->file);
                        args->rsvd2 &= GENMASK_ULL(31, 0); /* keep in-fence */
                        args->rsvd2 |= (u64)out_fence_fd << 32;
                        out_fence_fd = -1;
                } else {
                        fput(out_fence->file);
                }
        }
        i915_request_put(eb.request);

err_batch_unpin:
        if (eb.batch_flags & I915_DISPATCH_SECURE)
                i915_vma_unpin(batch);
err_parse:
        if (batch->private)
                intel_gt_buffer_pool_put(batch->private);
err_vma:
        if (eb.trampoline)
                i915_vma_unpin(eb.trampoline);
        eb_unpin_engine(&eb);
err_context:
        i915_gem_context_put(eb.gem_context);
err_destroy:
        eb_destroy(&eb);
err_out_fence:
        if (out_fence_fd != -1)
                put_unused_fd(out_fence_fd);
err_in_fence:
        dma_fence_put(in_fence);
err_ext:
        put_fence_array(eb.fences, eb.num_fences);
        return err;
}

static size_t eb_element_size(void)
{
        return sizeof(struct drm_i915_gem_exec_object2);
}

static bool check_buffer_count(size_t count)
{
        const size_t sz = eb_element_size();

        /*
         * When using LUT_HANDLE, we impose a limit of INT_MAX for the lookup
         * array size (see eb_create()). Otherwise, we can accept an array as
         * large as can be addressed (though use large arrays at your peril)!
         */

        return !(count < 1 || count > INT_MAX || count > SIZE_MAX / sz - 1);
}

/*
 * Legacy execbuffer just creates an exec2 list from the original exec object
 * list array and passes it to the real function.
 */
int
i915_gem_execbuffer_ioctl(struct drm_device *dev, void *data,
                          struct drm_file *file)
{
        struct drm_i915_private *i915 = to_i915(dev);
        struct drm_i915_gem_execbuffer *args = data;
        struct drm_i915_gem_execbuffer2 exec2;
        struct drm_i915_gem_exec_object *exec_list = NULL;
        struct drm_i915_gem_exec_object2 *exec2_list = NULL;
        const size_t count = args->buffer_count;
        unsigned int i;
        int err;

        if (!check_buffer_count(count)) {
                drm_dbg(&i915->drm, "execbuf2 with %zd buffers\n", count);
                return -EINVAL;
        }

        exec2.buffers_ptr = args->buffers_ptr;
        exec2.buffer_count = args->buffer_count;
        exec2.batch_start_offset = args->batch_start_offset;
        exec2.batch_len = args->batch_len;
        exec2.DR1 = args->DR1;
        exec2.DR4 = args->DR4;
        exec2.num_cliprects = args->num_cliprects;
        exec2.cliprects_ptr = args->cliprects_ptr;
        exec2.flags = I915_EXEC_RENDER;
        i915_execbuffer2_set_context_id(exec2, 0);

        err = i915_gem_check_execbuffer(&exec2);
        if (err)
                return err;

        /* Copy in the exec list from userland */
        exec_list = kvmalloc_array(count, sizeof(*exec_list),
                                   __GFP_NOWARN | GFP_KERNEL);
        exec2_list = kvmalloc_array(count, eb_element_size(),
                                    __GFP_NOWARN | GFP_KERNEL);
        if (exec_list == NULL || exec2_list == NULL) {
                drm_dbg(&i915->drm,
                        "Failed to allocate exec list for %d buffers\n",
                        args->buffer_count);
                kvfree(exec_list);
                kvfree(exec2_list);
                return -ENOMEM;
        }
        err = copy_from_user(exec_list,
                             u64_to_user_ptr(args->buffers_ptr),
                             sizeof(*exec_list) * count);
        if (err) {
                drm_dbg(&i915->drm, "copy %d exec entries failed %d\n",
                        args->buffer_count, err);
                kvfree(exec_list);
                kvfree(exec2_list);
                return -EFAULT;
        }

        for (i = 0; i < args->buffer_count; i++) {
                exec2_list[i].handle = exec_list[i].handle;
                exec2_list[i].relocation_count = exec_list[i].relocation_count;
                exec2_list[i].relocs_ptr = exec_list[i].relocs_ptr;
                exec2_list[i].alignment = exec_list[i].alignment;
                exec2_list[i].offset = exec_list[i].offset;
                if (INTEL_GEN(to_i915(dev)) < 4)
                        exec2_list[i].flags = EXEC_OBJECT_NEEDS_FENCE;
                else
                        exec2_list[i].flags = 0;
        }

        err = i915_gem_do_execbuffer(dev, file, &exec2, exec2_list);
        if (exec2.flags & __EXEC_HAS_RELOC) {
                struct drm_i915_gem_exec_object __user *user_exec_list =
                        u64_to_user_ptr(args->buffers_ptr);

                /* Copy the new buffer offsets back to the user's exec list. */
                for (i = 0; i < args->buffer_count; i++) {
                        if (!(exec2_list[i].offset & UPDATE))
                                continue;

                        exec2_list[i].offset =
                                gen8_canonical_addr(exec2_list[i].offset & PIN_OFFSET_MASK);
                        exec2_list[i].offset &= PIN_OFFSET_MASK;
                        if (__copy_to_user(&user_exec_list[i].offset,
                                           &exec2_list[i].offset,
                                           sizeof(user_exec_list[i].offset)))
                                break;
                }
        }

        kvfree(exec_list);
        kvfree(exec2_list);
        return err;
}

int
i915_gem_execbuffer2_ioctl(struct drm_device *dev, void *data,
                           struct drm_file *file)
{
        struct drm_i915_private *i915 = to_i915(dev);
        struct drm_i915_gem_execbuffer2 *args = data;
        struct drm_i915_gem_exec_object2 *exec2_list;
        const size_t count = args->buffer_count;
        int err;

        if (!check_buffer_count(count)) {
                drm_dbg(&i915->drm, "execbuf2 with %zd buffers\n", count);
                return -EINVAL;
        }

        err = i915_gem_check_execbuffer(args);
        if (err)
                return err;

        exec2_list = kvmalloc_array(count, eb_element_size(),
                                    __GFP_NOWARN | GFP_KERNEL);
        if (exec2_list == NULL) {
                drm_dbg(&i915->drm, "Failed to allocate exec list for %zd buffers\n",
                        count);
                return -ENOMEM;
        }
        if (copy_from_user(exec2_list,
                           u64_to_user_ptr(args->buffers_ptr),
                           sizeof(*exec2_list) * count)) {
                drm_dbg(&i915->drm, "copy %zd exec entries failed\n", count);
                kvfree(exec2_list);
                return -EFAULT;
        }

        err = i915_gem_do_execbuffer(dev, file, args, exec2_list);

        /*
         * Now that we have begun execution of the batchbuffer, we ignore
         * any new error after this point. Also given that we have already
         * updated the associated relocations, we try to write out the current
         * object locations irrespective of any error.
         */
        if (args->flags & __EXEC_HAS_RELOC) {
                struct drm_i915_gem_exec_object2 __user *user_exec_list =
                        u64_to_user_ptr(args->buffers_ptr);
                unsigned int i;

                /* Copy the new buffer offsets back to the user's exec list. */
                /*
                 * Note: count * sizeof(*user_exec_list) does not overflow,
                 * because we checked 'count' in check_buffer_count().
                 *
                 * And this range already got effectively checked earlier
                 * when we did the "copy_from_user()" above.
                 */
                if (!user_write_access_begin(user_exec_list,
                                             count * sizeof(*user_exec_list)))
                        goto end;

                for (i = 0; i < args->buffer_count; i++) {
                        if (!(exec2_list[i].offset & UPDATE))
                                continue;

                        exec2_list[i].offset =
                                gen8_canonical_addr(exec2_list[i].offset & PIN_OFFSET_MASK);
                        unsafe_put_user(exec2_list[i].offset,
                                        &user_exec_list[i].offset,
                                        end_user);
                }
end_user:
                user_write_access_end();
end:;
        }

        args->flags &= ~__I915_EXEC_UNKNOWN_FLAGS;
        kvfree(exec2_list);
        return err;
}

#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
#include "selftests/i915_gem_execbuffer.c"
#endif